Return bend



A ril 5 1932.. D. BRANDT 1,853,012

RETURN BEND Filed July 20, 1926 I u I" l 3 044 oz fluow Patented Apr. 5, 1-932 FFI CTE DAVID G. BRANDT, 0F WESTFIELD, NEW JERSEY, ASSIGN'OR T0 DOHERTY RESEARCH COMPANY, OF NEW YORK, N. Y.,

A CORPORATION OF DELAWARE nnrunn BEND Application filed July 20,

The present invention relates to return bends and has for one of its principal objects the provision ofa return bend which shall be tight against hot oil under high pressure and which shall be at the same time durable and readily assembled.

A further object of the present invention is to provide a construction adapted for use in pipe stills which shall be of simple and durable construction and convenient to manufacture.

' The novel features of the present invention are pointed out with particularity in the appended claims. The invention, itself, however, together with further objects and. advantages will best be understood from the following description taken in connection with theaccompanying drawings in which Fig. 1 is an elevational view, parts being shown in section and parts being broken away for purposes of illustration, the sectioned portion of Fig. 1 being taken on line 11 ofFig. 2.

' Fig. 2 is aplan of the device illustrated in Fig. 1.

Fig. 3 is aside view of the device shown in Fig. 1.

Fig. 4 is an enlarged detail of a sectional portion of Fig.1.

Fig. 5 is a detail of a bolt anchor arrangement used in the device illustrated in Figs. 1 and 2.

In the drawings, 10 and 12 are tubes of a pipe still or similar apparatus in which oil is heated to a comparatively high temperature and under a comparatively high pres sure. The oil or fluid will be understood to go through tubes 10 and 12 in series, the ends of these tubes being connected by a return bend 14:. Tubes 10 and 12 are tapered at their ends as illustrated at 18 and the portions 18 project within the open ends of bend 14.

Apparatus of the character in question is intended to be tight against hot petroleum or like fluid at a temperature of over 800 F. and a pressure of 250 lbs. gage. \Vhile it has been attempted heretofore to use return bends for connecting the ends of tubes in usein pipe stills the difiiculties encountered have been such that the great majority of 1926. Serial No. 123,698.

pipe stills in use today for oilheating purposes utilize H-shaped headers for this purpose, the ends of the tubes being expanded. into the headers. The header type construction is more expensive and has other disadvantages as compared to the return bend construction. However, it has been found necessary to use gaskets in the return bends and, as the pressures and temperatures in use in the petroleum cracking processhave been increased, increasing difliculties have been encountered with gasket constructions, resulting in the elimination of return bends from a great majority of pipe stills used for cracking petroleum. The gaskets heretofore used in pipe stills which have given the most promising results have been of copper. The temperatures and flue pressures in use in petroleum pipe stills at the present time are such that the mechanical pressure required to be put on the copper in order to make a tight joint, at above 7 F., causes the copper to flow and therefore to thin out to an undesirable degree, resulting in frequent leaks. The copper is also attacked by the sulphur in the oil at these relatively high temperatures. Gaskets made from ordinary bronzes and from aluminum have been experimented with without obtaining results better than those produced when using copper gaskets.

According to the present invention aluminum bronze gaskets 16 are used between the return bend 14 and the bevelled ends 18 of the tubes 10 and 12. The aluminum bronze has been found to resist the attack of sulphur in the petroleum at temperatures above 800 and pressures well above 200 lbs. moreover, although soft enough to seat tightly against the opposed surfaces of the bend and of the tubes, it does not deform under the high mechanical pressures required to obtain a liquid tight joint even at the temperatures mentioned. The aluminum bronze for use according to the present invention has an averagecompos'ition of approximately 8% aluminum, 91% copper, and 1% iron by weight.

The relative percentages of aluminum and copper mayvary to some extent but the maximum and minimum limits of aluminum considered desirable are 10% and 7% respectively. It will be observed that aluminum bronze possesses both chemical and mechanical characteristics enabling it to withstand the severe conditions to which it is subjected in accordance with the present invention. As illustrated and according to the present invention, the gaskets 16 are rings whose crosssections are quadrilaterals having two parallel sides. These gaskets are seated under high hydraulic pressure in sockets 20 designed to receive them and counter-sunk in the mouths of the return bend 14. The walls 22 ofthe sockets 2O flare outward slightly as illustrated in Figs. 1 and 4 so that the gaskets 16 may be forced into place against wedging resistance. The inner ends of the sockets 20, moreover, are made, according to the present invention, in the form of definite shoulders 24 projecting at right angles to the axis of the bend at its mouths. The gaskets 16 are firmly seated against the shoulders 24. It will be seen that the cross-section of gaskets 16 has two sides complemental to side 22 and shoulder 24 respectively of sockets 20 and that a third side of gaskets 16 is complemental to the tapered face of the ends 18 of tubes 10 and 12. As a result of the construction of the sockets 20 and gaskets 16 just described, and the method of inserting the gaskets, the gaskets 16 become during use practically an lntegral part of the return bends being held firmly in sockets 20 by friction. It is, however, possible to remove the gaskets 16 from the bends 14 whenever desired, the bends having been removed from the tubes, by striking the bends with a hammer. Owing to the flaring shape of the sockets 20 the vibration produced by the hammering on bends14 causes gaskets to work loose from their sockets. Ordinarily, however, there is no need to remove the gasket 16 from the bends 14, it being possible to remove a bend 14 from stills repeatedly for purposes of cleaning the tubes 10 and 12 and to return the bend to use with the same gaskets. When, however, bends are removed from the tubes, there is no tendency of the tubes to stick to the gasketsthe parts coming away readily and the gasket-s 16 acting as if part of the bends 14 as previously mentioned. It will be seen from the drawings that the metal of the tubes 10 and 12 does not contact in any way with the metal of the bends 14 except on the surfaces of the gaskets 16 The tubes 10 and 12 are connected to the return bends 14 when the parts are in assembled position by bolts 26 which are threaded into flanges 28, the flanges in turn being threaded directly on to the ends of the tubes 10 and 12. Return bends such as 14 are provided with apertured shoulders 30 through which the bolts 26 extend, and nuts 32, 32 are used at the ends of the bolts 26 opposite the flanges 28 to draw the parts firmly together.

By tightening up the nuts 32 almost any desired pressure can be exerted between the bevelled ends 18 of the tubes 10 and 12 and the faces of the gaskets 16-with which the ends 18 are in contact, the pressure on the nuts being multiplied by the wedging contact between ends 18 and the gaskets.

- When assembled in a pipe still or apparatus for cracking oil the tubes are supported preferably by means of a tube sheet such as 34. According to the present invention, tubes 10 and 12 are secured to the late or sheet 34 by such arangement including lugs 36, 36 projecting from the flanges 28, 28. The lugs 36, 36 are arranged in line with the centersof the tubes 10 and 12 and rest on a socket 38 formed integral with or fixed to, the surface of plate 34 on the side toward the return bend 14. Preferably a washer 40 is inserted between the lugs 36' and the socket 38. The socket 38 is, in general, of a U-shaped form in plan as illustrated in Fig. 5. It has a U-shaped opening 41 for reception of the shank 42 of a bolt and the lower end of the opening or aperture 41 is undercut to produce a chamber 44 for the reception of the head 46 of the bolt. The threaded end of the bolt projects beyond the lugs 36, 36 which lie adjacent the shank 42 and a nut 48 on the outer end of the shank 42 serves to force the lugs 36 down tight against the socket 38 thereby securing the tubes 10 and 12 firmly to the plate 34.

It will be seen that the present invention permits the construction of pipe stills without delay or expense due to expanding the tubes into headers. Moreover, the apparatus as a whole is inexpensive, durable and readily assembled and disassemble Having thus described my invention, I claim:

1. In a pipe-still for petroleum, the combination of a tube having a bevelled end, a return bend having one end surrounding said end of said tube, and a gasket of aluminum bronze interposed between said tube and said bend.

2. In a pipe still for petroleum, the combination of, a return bend havin acountersunk socket at its mouth, a tu having a bevelled end projecting into said mouth, and

a gasket of aluminum'bronze having a crosssection whose sides are complementary to the surfaces of saidsocket and said bevelled end anld lying in liquid tight contact with said tu e.

3. In a pipe still for etroleum the combination of a return ben having a socket at its mouth, said socket flaring out-wardl to a slight extent-and the bend having an a rupt shoulder at the inner end of the socket, and a gasket of aluminum bronze seated against said shoulder and firmly held in the socket by friction, said gasket having a face adapted to contact with the bevelled end of a tube and making a small angle with the axis of the opening through the bend at its mouth.

4. In a plpe still the combination of a tube sheet, tubes extending through said sheet, a return bend connecting the ends of two said tubes on one side of said sheet, a socket member fixed to said sheet and having an undercut chamber therein, a bolt having its head in said chamber, and means associated with said bolt for attaching said tubes and bend to said sheet.

5. A pipe still for heating petroleum, comprising a tube sheet, a pair of pipes extending through said sheet, said pipes adapted to receive a return bend, means on said pipes for detachably securing a return bend thereto, and means for holdin the ends of said pipes in a relatively fixe position with respect to said tube sheet, thereby permitting the ready attachment of the ends of a return bend.

6. In a tubular still for mineral oil distillation, a tube sheet, a pair of tubes one end of each of which extends through said sheet, a detachable return bend normally connecting the extending ends of said tubes, and

means for holding the ends of said tubes in V a substantially fixed position with respect to said tube sheet and for retaining said ends in a substantially fixed position with respect to each other when said return bend is detached therefrom.

7. In a tubular heater for heating oils containing sulphur to a high temperature, a coupling comprising a gasket containing-the metals copper and aluminum.

8. In a tubular heater for heating oils containing sulphur to a high temperature, a coupling comprising analuminum bronze gasket containing from 7% to 10% of aluminum.

9. In a tubular heater for heating oils con taining sulphur to a high temperature, a coupling comprising an aluminum bronze gasket containing approximately 8% aluminum, 91% copper and 1% iron.

In testimony whereof I aflixmy signature.

DAVID G. BRANDT.

being 

